WASHINGTON -- A lobbying reform bill introduced by Democratic leaders in the U.S. Congress could force grass-roots organizations to disclose portions of their donor lists.

The Honest Leadership and Open Government Act of 2007, introduced Tuesday by Democratic leaders, would force coalitions and associations including the Sierra Club, the National Rifle Association and NARAL Pro-Choice America to disclose lobbying activities, The Hill newspaper reported Thursday.

The bill also includes a provision that could require nonprofit groups, trade associations and unions to release the names of donors who give more than $500 during a three-month period.

"The new section 206 has been radically altered," said Douglas Johnson, the legislative director of the National Right to Life Committee, which opposes the provision.

"This new provision, unless it's changed, is going to touch off a firestorm that even exceeds the controversy over (the) grass-roots provision," he told The Hill. "It would require every nonprofit advocacy organization to report its donors over $500."